The installation of conventional foundation piles has previously been accomplished by driving a precast concrete pile or steel beam or vibrating an H pile into a soil bed. When driving a foundation pile, the soil surrounding the pile may be compacted in various ways as well as disrupted by the seismic shocks of the pile driver itself. When driving a pile into hard ground, earth displaced by the pile causes the ground surrounding the pile to heave. In contrast, when driving a pile into soft ground, settling of the surrounding soil may be caused. All of these conditions can cause problems for any standing structures in the area of the pile being driven.
The installation of conventional piles has also previously been accomplished by pre-drilling a hole in a soil bed using an auger and lowering a pre-molded pile into the hole. A hybrid system also exists between the driving and drilling methods whereby an open ended pile such as a pipe pile is driven into a soil bed, after which point the soil inside the pile is augered out and concrete is poured in the cavity formed therein. Cast and hole methods as well as casons may also be used, specifically where there are concerns for preserving nearby buildings against the problems discussed above. However, all these methods can prove either costly and/or slow to carry out in the field. Furthermore, where the ground in a job site is deemed to be contaminated, any soil removed from the ground, such as that produced by an auger, must be disposed of properly presenting an additional problem and associated cost.
A more complex system is known whereby a pile is attached to a drill head which is substantially larger than the diameter of the pile itself. The pile is turned together with the drill head by a drilling rig to create a passage in the soil bed through which the pile may pass. A conduit is provided through the center of the pile for water or grout to be pumped down and out the tip of the drill head to either float away debris or anchor the pile in its final resting place in the soil bed. Another system, known as an under-reamer system, features a double torque head which turns a drill in the center of a pipe, which pipe is itself turned in the opposite direction from the drill. Although they do have certain advantages over other known systems, both of these drilling systems are obviously substantially more complex, and therefore more costly than the first several prior art systems discussed.
Both driving and drilling systems used to place foundation piles rely in part on brute force to either force a pile into a soil bed, or to cut and remove material. What is needed is a more elegant approach to foundation pile placement providing such benefits as may include a faster pile placement speed, lower cost and greater ease of use as well as higher load capacity piles.